1. Field of the Invention
The present invention relates to a waterproof slide fastener and more particularly, to a continuous-coil type waterproof slide fastener.
2. Description of Related Art
Slide fasteners are commonly seen in daily life and often deemed as necessary fastening devices; due to the property of easily being closed or open, a slide fastener is adopted in various applications, such as garments, bags, tents or skiwear involved.
Because slide fasteners are adopted in various objects, they can be seen on various occasions, but those slide fasteners adopted in garments of sports or devices of the outdoors, like skiwear, windbreaks, raincoats, tents, or those adopted in snow or travel equipments, even like a sleeping bag, are all subject to nature test, the weather for instance.
For achieving the function of wind breaking and waterproof, materials of nylon or cloth processed with a water-repellent finishing are used as fabrics for making skiwear of outdoors and a waterproof interlining is also provided, thus a waterproof function is obtained. There is a disadvantage on a slide fastener when applied as a fastening device on the skiwear in view of waterproof function, for the whole waterproof property may not be totally provided. Moreover, in operation, a chink defined the central slit between the support tapes and the coupling elements of a slide fastener would be enlarged by an transversal external force, which is the most difficult issue needed to be addressed to for a waterproof slide fastener, because such disadvantage would lower the whole waterproof property or even lose the whole waterproof function.
In view of the aforesaid drawbacks, improved slide fastener structures are created to provide a waterproof function. Regular nylon slide fasteners, i.e. continuous-coil type slide fasteners include three types: (1) capable of prohibiting water penetration under zero external pressure; (2) capable of prohibiting low pressure water penetration; and (3) capable of prohibiting high pressure water penetration. Regular waterproof slide fasteners commonly have a fluid impervious film (layer) covered on one side of each support tapes.
According to the aforesaid type (1), a fluid impervious film is bonded to each support tape to repel water. Exemplars of this design are seen in Taiwan Patent No. 1220106; U.S. Pat. Nos. 3,764,437; 4,580,321; 4,596,065; 4,607,416; 4,724,586; 6,105,214 and 6,427,294. These disclosures show only the relative positioning difference between the fluid impervious film and the support tape. With respect to the central slit between the two support tapes, the aforesaid disclosures commonly teach the way to have the left and right sided fluid impervious film layer protrude over the inner longitudinal edge of the associating support tape so that the two fluid impervious films are squeezed against each to curve upwards for prohibiting penetration of water when the slide fastener is closed. However, when operating a slide fastener, a transverse tensile force will be produced and applied to each support tape to stretch open the central slit between the two support tapes and the two rows of coupling elements, causing an enclosure failure and permeation of water.
Further, if the fluid impervious film protrudes upwards, a special design of slider, for example, the slider of U.S. Pat. No. 6,622,351 shall be used, avoiding damage of the fluid impervious film caused by the slider. In this case, the range of application of the slide fastener is limited.
Further, Taiwan Patent No. 1220106 discloses a waterproof slide fastener, which has the fluid impervious film bonded to the two support tapes subject to the curvature of the fabric surface. After installation, the fluid impervious film is high stretched. After the fluid impervious film is cut off along the central slit between the two support tapes, the inner longitudinal edge of each support tape is exposed to the outside of the fluid impervious film. Thus, water permeation due to a capillary effect may occur.
Exemplars of continuous coil type slide fasteners that are capable of prohibiting permeation of pressured fluid are seen in U.S. Pat. Nos. 3,389,441; 3,501,816; 4,112,150 and 5,437,888. These patents teach filling and wrapping of a fluid impervious material in and about each row coupling elements to prohibit permeation of water through the two rows of the coupling elements of the slide fasteners. The fluid impervious film is arranged on the support tape as the same side as the associating row of coupling elements as shown in FIG. 2 of the U.S. Pat. No. 3,501,816. Further, U.S. Pat. No. 3,668,745 discloses an invisible waterproof slide fastener using metal coupling elements for interlocking. These slide fasteners must use a specially designed slider to move the coupling elements into the locking condition. FIG. 3 of U.S. Pat. No. 3,668,745 and FIG. 5 of U.S. Pat. No. 6,622,351 disclose different sliders for this application. These waterproof slide fasteners and sliders do not fit the environmental protection and fashion requirements for a product having light, thin, short and small characteristics.